George G. Elliott was a son of Sir Charles B. Elliott*, the first general manager of the Cape Government Railways. George attended the South African College, Cape Town, from 1888 to 1890, but does not appear to have obtained any formal qualification. He then started his career in the railways. During the Anglo-Boer War (1899-1902) he remained on railway duty in the Cape Colony, Orange River Colony (now the Free State) and the Transvaal. At some time before 1908 he visited the United Kingdom, where he gained some limited experience on British railways. In November 1906 he married Jessie Mildred Stubbs.
By 1908 Elliott was a locomotive superintendent on the Central South African Railways (CSAR), stationed in Johannesburg, and was also Captain of the CSAR Volunteers. On 1 July 1910, following the formation of the Union of South Africa, he was appointed as mechanical engineer in the newly formed South African Railways and Harbours. Around this time he contributed a paper on "Modern locomotive practice in South Africa" to the Journal of the Transvaal Institute of Mechanical Engineers (1909/10, Vol. 8, p. 224). Some years later he was awarded the gold medal of the South African Institution of Engineers for the year 1919/20, for a paper on the properties of white metals.